1. Field of the Invention
The present invention relates to a surface-treatment apparatus, and more particularly, to a surface-treatment apparatus for forming a photoresist-isolating wall on a panel.
2. Description of the Prior Art
Currently, an organic electroluminescent diode (OELD) panel with light weight, high contrast, fast response speed, low power consumption and high brightness becomes the focus of the innovative generation panel. However, compared with other mature panels, since the OELD panel is the latest without perfect techniques available, there are many difficulties in commercialization and mass production.
In the prior art of forming the OELD panel, a plurality of photoresist-isolating walls is perpendicularly formed on a plurality of anode electrodes to be a shadow mask. An organic electroluminescent layer and a cathode electrode are then evaporated ont he anode electrodes between two adjacent photoresist-isolating walls. However, when the cross section of the photoresist-isolating wall is approximately rectangular, the cathode electrodes on the top of the photoresist-isolating wall easily laterally diffuse to contact the anode electrodes during the evaporation. It will cause a short circuit, especially when the thickness of the photoresist-isolating wall is less than 4 xcexcm. In the technology disclosed in U.S. Pat. No. 5,962,970, such a photoresist-isolating wall is manufactured as a reverse-trapezoid cross section wherein the top is wider than the bottom to form a protruding portion. Yet, there are still several difficulties described hereinafter. First, the height (or thickness) of the photo-resist-isolating wall with the reverse-trapezoid cross section is limited. If the height is less than 4 xcexcm, the protruding portion will become too small to segregate the lateral diffusing cathode materials and the anodes. It is also incapable of improving the resolution of the current panel with less than 10 xcexcm linewidth. If the height is more than 4 xcexcm, the photoresist-separating wall is apt to collapse. Also, it does not fit in the market requirement in the thin, light, short and compact display. Second, the protruding portion of the reverse-trapezoid is not easily controlled. The formation of the photoresist-isolating walls with the reverse-trapezoid cross section comprises an exposure through a mask to define a pattern and a development to shape the walls. Yet, since there are many limitations in the exposure and the development, it is difficult to form the expected reverse-trapezoid cross section. Also, the following evaporation of the organic electroluminescent layer reduces the protruding portion of the wall. When the cathode electrode is next evaporated on the organic electroluminescent layer, it is possible to connect the cathode electrode and the anode electrode and cause the short circuit.
In the technology disclosed in U.S. Pat. Ser. Nos. 6,013,538, another photoresist-isolating wall is manufactured as a T-shaped top by multi-layer undercutting. Nevertheless, the multi-layer undercutting which comprises repeatedly coating, developing and etching has difficulties in controlling the thickness, the linewidth and the accuracy of the pattern. Also, the procedure is too complex to ensure the manufacturing quality and the production cost is too expensive to apply to the mass production. In consideration of the above mentions, it is needed to provide a surface-treatment apparatus to form the photoresist-isolating wall with the T-shaped top and avoid causing the above-mentioned disadvantages.
It is therefore a primary objective of the present invention to provide a surface-treatment apparatus for forming a photoresist-isolating wall with a T-shaped top on an OELD panel to avoid a short circuit.
In a preferred embodiment, the present invention provides a surface-treatment apparatus for forming a plurality of photoresist-isolating walls on an organic electroluminescent panel. The surface-treatment apparatus comprises a photoresist-coating module, a prebaking unit, an exposure unit, a post-exposure surface treatment module with an alkaline atmosphere, a development module and a hard baking unit. The photoresist-coating module coats a photoresist layer on the surface of the organic electroluminescent panel. The prebaking unit bakes the photoresist layer on the organic electroluminescent panel by a heating plate and initially drives solvents from the photoresist layer. The exposure unit performs an UV exposure process on the photoresist layer after the prebaking. The post-exposure surface treatment module with an alkaline atmosphere bakes the photoresist layer by a heating plate after the exposure process, wherein the alkaline atmosphere terminates a self-catalyzed reaction of photo-acid ions on the surface of the photoresist layer. The development module performs a developing process on the photoresist layer after the post-exposure surface treatment so as to form the plurality of photoresist-isolating walls with a T-shaped top. The hard baking unit bakes the plurality of photoresist-isolating walls by a heating plate, further reduces the solvents remaining in the photo-resist-isolating walls, and intensifies the strength and stability of photoresist-separating walls.
It is an advantage of the present invention that the surface-treatment apparatus improves the quality of the photoresist-isolating walls and lowers the production cost and failure. Also, the surface-treatment apparatus can be applied to manufacture an OELD panel with better resolution and production yield.